This invention relates to moisture sensing devices, and in particular to an improvement in devices for detecting urine and awaking enuretic children and adults.
Enuresis, particularly of the nocturnal type poses a vexing problem that is common especially among children and adolescents as well as among the elderly. Not surprisingly, many of those affected by enuresis are deep sleepers. Numerous devices have been proposed to sense the occurrence of bedwetting and to awaken the user upon the discovery thereof. Early such devices involved placing under the user's bed a sheet of a water permeable insulate, such as cotton, sandwiched by two pieces of metal foil, of which the top foil was perforated to allow the passage of urine. Upon wetting with electrolytic urine, the insulating layer becomes conductive and with suitable electronics, an alarm is sounded, awakening the user. Most recent such inventions are of a portable type, to be worn by the user within or in place of his undergarments. These offer the advantage of an improved response time, that is, they exhibit a shorter lag time between urination onset and its detection. These portable versions have several drawbacks, the overcoming of which is the object of the present invention. First is the limited area of detection imposed by such portable sensors. Buttonlike sensors, such as those described in U.S. Pat. Nos. 4,271,406 and 3,530,855 exhibit the highest vulnerability to being entirely missed by the flow of urine, especially for boys. Similarly, strip sensors, such as that presented in U.S. Pat. No. 4,191,950, do not provide sensitivity over the entire perineal area. Second, is the degraded response time presented by sensors which do not cover the entire perineal area. Such sensors depend on a lateral urine flow across the perineal area to the active area of the sensor. This can present a considerable delay in cases of sensor misalignment, a problem particularly pronounced with boys. This is a special problem for small sensors, such as the buttonlike sensors previously mentioned, as well as for larger sensors which do not maintain sensitivity throughout the full area of the sensor, such as the edge-sensitive strip described in the preferred embodiment of U.S. Pat. No. 4,191,950. Third, is the drawback that many previous designs incur higher production costs due to sensor complexity and to special processing involved in the fabrication thereof, the perforation of conductive layers being particular among these.